Bowling pin and base



wil f p 1963 w. L. JOLITZ ET AL 3,104,105

BOWLING PIN AND BASE Filed Dec. 10, 1959 u/M UZZZM 3 llam s United States Patent f a corporation of Delaware Filed Dec. 10, 1959, Ser. No. 858,766

5 Claims. (Cl. 273-82) This invention relates to bowling pins and more particularly to a bowling pin including a molded base.

Bowling pins are normally made of wood and the continued impact of the bowling ball upon the pin tends to damage the pin so that slivers or fractured segments are broken from the side of the pin. The slivers or fractured segments generally extend to the base on which the pin stands, thus damaging the base. At this point, of course, the pin must be discarded or be repaired.

It has been found that the problem of splintering near the base of the pin may be obviated by including a molded base or bottom which is generally inserted into an aperture in the pin and which is designed to prevent such splintering and remain unaffected by usage so as to materially lengthen the life of the pin. However, the use of such a base presents addition-a1 problems since the base must provide physical characteristics similar to the wooden pin itself. Bases made with materials which do not approach such characteristics have resulted in drastically reduced bowling scores.

In producing a base which is satisfactory for use as a bowling pin base, it is necessary that both the hardness of the material for durability purposes be considered and that the material have the desired physical characteristics of slip. Slip may be defined as the resistance to motion or impact due to the frictional forces between the impacted object and the material on which the object is resting. A bottom or pin base can control the score of a pin as a result of slip in at least two areas of action. First, as the pin is impacted with the hall, the slip of the bottom can control the amount and timing of the relative vertical and horizontal movements of the pin. Therefore, there must be an optimum slip point at which maximum pin-to-pin and pinto-kickback action occurs. Secondly, many pin-to-pin and pin to-kick-back rebounds result from contact on the bottom. Therefore, the hardness and resiliency of the bottom or base material can materially affect this action.

It is, therefore, an object of this invention to provide a bowling pin which has a molded base portion having the desirable physical properties of hardness and slip, thus overcoming the problems described above.

It is a further object of this invention to provide a bowling pin which comprises a body portion of the required shape and a molded base portion having the desired properties of slip and hardness attached thereto, the base portion comprising a fused mixture of an unextracted polyoaprolactam resin and a synthetic linear interpolyamide.

Other objects and advantages of this invention will become apparent from the following description taken together with the accompanying drawings.

Of the drawings:

FIGURE 1 is a side elevational view partially in section showing the bowling pin of this invention including a molded base portion; and

FIGURE 2 is an enlarged top plan view of the molded base portion.

Referring now to the drawings, a bowling pin of conventional size and shape is shown including a molded base portion 11 which is inserted into a recess 10a in the pin 10. The molded base is cylindrical in shape, having an open center 1102 and a thickened lower portion 11b.

The thickened lowerportion is of a diameter such that it continues the side dimension 10b of the bowling pin to make a continuous outer surface.

The molded base 11 is a fused mixture of an unextra'cted polycaprolactam resin and a synthetic linear interpolyamide. It will be understood that in this specification, the term polycaprolactam is used to designate the polymerization product of 6-amino caproic acid which is sometimes also referred to. as epsilon-amino oaproic acid.

The linear interpolyamides usable in this invent-ion are produced by heating to reaction temperature at least threepolyarnide-form-ing reactants such as a primary diamine, a dibasic carboxylic acid and la polymerizable monoaminomono-carboxylic acid such as are shown in U.S. Patent No. 2,252,555 which is included herein by reference. In producing these polyamides, it is also possible to use the salt of a diamine and a dibasic acid together with a polymerizable monoaminomono-carboxyli-c acid. The heating range adaptable for the production of these linear interpolyamides is generally in the range of from about 180 to 300 C. The reaction is generally carried on in the presence of a diluent under conditions which will permit the water formed in the reaction to escape. Solvents or diluents which may be used are,

.for example, phenol, the cresols, the zyleneols, diphenolol propane and o-hydroxy diphenol. also be carried out in water.

As an example of the interpoly-amide which is particularly desirable for the production of the pin base of this invention, a mixture of 5 parts of methyl caprolactam (obtained by isomerization of 3-methyl cyclohexanone oxiine), 5 parts of hexamethylene diammonium adipate and 0.5 part of water was heated for 24 hours in a sealed tube at 250 'C. and then for two hours at 255 C. at atmospheric pressure in an oxygenated free atmosphere. The intenpolymer produced had a softening point of about 65 C. and an intrinsic viscosity of 0.7. All parts mentioned in the above example are by weight of the The reaction may resulting resin. For ease of description hereafter, the' resin produced in this example will be referred to as resin X.

In producing the pin base of this invention, it is important that the proportions of the polycar-prolactam and resin X be closely controlled. -It has been determined that a satisfactory pin base can be produced from a resin mixture comprising from about 70 to 85 parts by weight of polyoaprolactam resin and 30 to 15 parts by weight of resin X. It is most preferred that the proportions of the two components be about 85 parts by weight of polyoaprolactam resin and 15 parts by weight of resin X. Again, the parts by weight referred to in this paragraph are by weight of the resulting pin base.

In compounding the materials mentioned above, the proportions of the polycaprolactam resin and resin X are physically and uniformly mixed in a conventional mixer, after which they are run through a ball mill to provide a comminuted substance which will generally pass through a mesh screen. After this step, the materials are reground until they are passed through a inch screen. Subsequently, the mixed and ground material is tumbled in a drum less than five-eights full for about ten minutes. The material is then ready for molding.

The pin base is prepared using the mixture described above by an injection molding process in a suitable mold. This molding operation is conducted at temperatures ranging from about 450' to 550 F. and at pressures ranging from about 1200 to about 2000 p.s.i. The temperature and the pressures use-d will, of course, vary as will the time of molding, in order to produce the desired pin base as is well known in the injection molding art. The

3 finished part is then cooled and then subsequently hydrated in boiling water for about two hours.

The pin base produced by the process described above is then ready for insertion into a bowling pin. In prepar' ing the pin, the bottom groove a is cut in the pin base by a conventional cutter. A conventional adhesive is then applied to the interior of the bottom groove and the pin base is inserted into position. A pressure is asserted against the pin base for a period necessary to allow the glue to set, giving optimum adhesion between the base and the pin.

The resultant bowling pin including the molded pin base is found to be very satisfactory for bowling purposes. The blended resin base has very acceptable properties of hardness and slip and the tendencies toward splintering and the like, are noticeably reduced.

Having thus described our invention as related to the embodiments shown in the accompanying drawings, it is our intention that the invention be not limited by any of the details of description unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.

We claim:

1. A bowling pin comprising: a body portion of required shape and a molded base portion having desired properties of slip and hardness attached thereto, said base portion comprising a fused mixture of a major proportion of an unextracted polycaprolactam resin and a minor proportion of a synthetic linear interpolyamide, said major proportion being about 3 times that of said minor proportion.

2. A bowling pin comprising: a body portion of re quired shape and a molded base portion having desired properties of slip and hardness attached thereto, said base portion comprising a fused mixture of from about 70 to 85 parts by weight of said base of an unextracted polycaproloctam resin and from about to 15 parts by weight of said base of a synthetic linear interpolyamide.

3. The pin of claim 2 where said resin is present in an amount of about 85 parts by weight of said base and said interpolyamide is present in an amount of about 15 parts by weight of said base.

4. A bowling pin comprising: a body portion of required shape and a molded base portion having desired properties of slip and hardness attached thereto, said base portion comprising a heat fused mixture of from about to parts by weight of said base of an unextraeted polycaprolactam resin and from about 30 to 15 parts by weight of said base of a synthetic linear interpolyamide comprising the reaction product of methyl caprolactam and hexamethylene diammonium adipate.

5. The pin of claim 4 wherein said resin is present in an amount of about 85 parts by Weight of said base and inteipolyamide is present in an amount of about 15 parts by weight of said base.

References Cited in the file of this patent UNITED STATES PATENTS 2,193,529 Coffman Mar. 12, 1940 2,339,237 Brubaker et a1 J an. 18, 1944 2,378,977 Brubaker June 26, 1945 2,517,116 Klinger Aug. 1, 1950 2,701,719 Di Pierro Feb. 8, 1955 2,852,485 Stott et a1. Sept. 16, 1958 2,964,319 Berry et al Dec. 13, 1960 

1. A BOWLING PIN COMPRISING: A BODY PORTION OF REQUIRED SHAPED AND A MOLDED BASE PORTION HAVING DESIRED PROPERTIES OF SLIP AND HARDNESS ATTACHED THERETO, SAID BASE PORTIION COMPRISING A FUSED MIXTURE OF A MAJOR PROPORTION OF AN UNEXTRACTED POLYCAPROLACTAM RESIN AND A MINOR PORPORTION OF A SYNTHETIC LINEAR INTERPOLYAMIDE, SAID 